From 96e6122cb79616c622ae0d025eb9f981120b568d Mon Sep 17 00:00:00 2001 From: Zheng Yejian Date: Thu, 10 Nov 2022 10:03:19 +0800 Subject: [PATCH] tracing: Optimize event type allocation with IDA MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit After commit 060fa5c83e67 ("tracing/events: reuse trace event ids after overflow"), trace events with dynamic type are linked up in list 'ftrace_event_list' through field 'trace_event.list'. Then when max event type number used up, it's possible to reuse type number of some freed one by traversing 'ftrace_event_list'. As instead, using IDA to manage available type numbers can make codes simpler and then the field 'trace_event.list' can be dropped. Since 'struct trace_event' is used in static tracepoints, drop 'trace_event.list' can make vmlinux smaller. Local test with about 2000 tracepoints, vmlinux reduced about 64KB: before：-rwxrwxr-x 1 root root 76669448 Nov 8 17:14 vmlinux after： -rwxrwxr-x 1 root root 76604176 Nov 8 17:15 vmlinux Link: https://lkml.kernel.org/r/20221110020319.1259291-1-zhengyejian1@huawei.com Signed-off-by: Zheng Yejian Acked-by: Masami Hiramatsu (Google) Signed-off-by: Steven Rostedt (Google) --- include/linux/trace_events.h | 1 - kernel/trace/trace_output.c | 66 +++++++++++--------------------------------- 2 files changed, 16 insertions(+), 51 deletions(-) diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h index 20749bd9db71..bb2053246d6a 100644 --- a/include/linux/trace_events.h +++ b/include/linux/trace_events.h @@ -136,7 +136,6 @@ struct trace_event_functions { struct trace_event { struct hlist_node node; - struct list_head list; int type; struct trace_event_functions *funcs; }; diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c index 67f47ea27921..f0ba97121345 100644 --- a/kernel/trace/trace_output.c +++ b/kernel/trace/trace_output.c @@ -11,6 +11,7 @@ #include #include #include +#include #include "trace_output.h" @@ -21,8 +22,6 @@ DECLARE_RWSEM(trace_event_sem); static struct hlist_head event_hash[EVENT_HASHSIZE] __read_mostly; -static int next_event_type = __TRACE_LAST_TYPE; - enum print_line_t trace_print_bputs_msg_only(struct trace_iterator *iter) { struct trace_seq *s = &iter->seq; @@ -688,38 +687,23 @@ struct trace_event *ftrace_find_event(int type) return NULL; } -static LIST_HEAD(ftrace_event_list); +static DEFINE_IDA(trace_event_ida); -static int trace_search_list(struct list_head **list) +static void free_trace_event_type(int type) { - struct trace_event *e = NULL, *iter; - int next = __TRACE_LAST_TYPE; - - if (list_empty(&ftrace_event_list)) { - *list = &ftrace_event_list; - return next; - } + if (type >= __TRACE_LAST_TYPE) + ida_free(&trace_event_ida, type); +} - /* - * We used up all possible max events, - * lets see if somebody freed one. - */ - list_for_each_entry(iter, &ftrace_event_list, list) { - if (iter->type != next) { - e = iter; - break; - } - next++; - } +static int alloc_trace_event_type(void) +{ + int next; - /* Did we used up all 65 thousand events??? */ - if (next > TRACE_EVENT_TYPE_MAX) + /* Skip static defined type numbers */ + next = ida_alloc_range(&trace_event_ida, __TRACE_LAST_TYPE, + TRACE_EVENT_TYPE_MAX, GFP_KERNEL); + if (next < 0) return 0; - - if (e) - *list = &e->list; - else - *list = &ftrace_event_list; return next; } @@ -761,28 +745,10 @@ int register_trace_event(struct trace_event *event) if (WARN_ON(!event->funcs)) goto out; - INIT_LIST_HEAD(&event->list); - if (!event->type) { - struct list_head *list = NULL; - - if (next_event_type > TRACE_EVENT_TYPE_MAX) { - - event->type = trace_search_list(&list); - if (!event->type) - goto out; - - } else { - - event->type = next_event_type++; - list = &ftrace_event_list; - } - - if (WARN_ON(ftrace_find_event(event->type))) + event->type = alloc_trace_event_type(); + if (!event->type) goto out; - - list_add_tail(&event->list, list); - } else if (WARN(event->type > __TRACE_LAST_TYPE, "Need to add type to trace.h")) { goto out; @@ -819,7 +785,7 @@ EXPORT_SYMBOL_GPL(register_trace_event); int __unregister_trace_event(struct trace_event *event) { hlist_del(&event->node); - list_del(&event->list); + free_trace_event_type(event->type); return 0; } -- 2.11.0